[antlr-interest] Tree parser for large (and changing) grammars

[Andreas Ravnestad]

Our XQuery project is moving along, and now we plan to write a tree
parser and convert the AST into relational algebra.

It seems a challenging part of the work will be to write the tree
grammar itself. A common approach seems to be "copy & paste", however
this creates a problem with maintainability since the rewrite rules in
the parser grammar will change over time as we work our way through
it.

Any ideas about how to make this as painless as possible? What is your
workflow for writing tree parser for large grammers?

Thanks,
Andreas